Hi Jeffrey, > Checkout https://forum.kde.org/viewtopic.php?p=66274 for some info on > detection of posix_memalign.
It's well-known that you can't use standards symbols like __STDC_VERSION__ or _XOPEN_SOURCE for hardly anything. We wouldn't have hundreds of AC_CHECK_FUNC calls in gnulib/m4/ if they weren't needed. > I think there's also another option, if interested. On x86 you can get > aligned allocations with _mm_malloc. _mm_malloc is not in the libc of any system I know of. The docs [1] state that it is a compiler built-in. If it relies on an Intel library, that would make it unsuitable for use in gnulib (since it would introduce an additional link dependency for something that should not need one). > And with PPC you can get an > aligned block with vec_malloc. On AIX, yes, not on Linux/PowerPC nor on Mac OS X/PowerPC. But the only documentation of this function that I can find [2] is not a reference documentation. Why would I use a function that has no reference documentation? > As you probably know, Linux aligns heap allocations to 16 by default. It's the libc which does this, not the kernel. And glibc aligns malloc() results to 8 bytes on most 32-bit platforms. Bruno [1] https://software.intel.com/sites/landingpage/IntrinsicsGuide/#text=_mm_free&expand=5236,3543 [2] https://www.ibm.com/support/knowledgecenter/ssw_aix_72/generalprogramming/vector_prog.html
